Furnace



v SSJS L. ROESSEL ET AL Feb. 26

FURNACE Filed May 4. 1921 Patented Feb. 26, 1924.

i' STATES LOUIS BOIEEL, OF BROOKLYN, NEW YORK; .ARTHUR E. BELLIS, OFSPRINGFIELD,

TO BELLIS HEAT TREATING COMPANY, OF NEW' HAVEN, CONNECTICUT, A. COR,-

POBATION OF CONNECTICUT.

FUENACE.

Application tiled Hay e,

To all whom t may concern.'

Be it known that we, Lome RoEssnL, a citizen of the United States, and aresldent of Brookl n, in the county of Kings and State of ew York,ARTHUR E. Banus, a citizen of the United States, and a resident of Sringiield, in the county of Hampden and tate of Massachusetts, andCHARLES S. COLLINS, a citizen of the United States, and a resident ofBronx, in the county of Bronx and State of New York, have invented newand useful Improvements in Furnaces, of which the following is aspecification.

This invention relates to furnaces and more particularly to furnaces ofthat general type which are used in the heat treatment of metals.

Generically considered, our present invention comprehends the provisionof a mult-iple type furnace designed for the purpose of most eiicientlyand economically utllizing the generated heat in the treatment of metalsor metal alloys in liquid baths.

More particularly, in one embodiment of the invention, we provide abattery of furnace chambers which may be produced in the form of oneunitary structure, or may consist of several independent furnacestructures together with means for supplying a reducing atmosphere forthe high temperature treatment of the metal or metal alloy to one of thefurnage chambers and means for conducting the high temperature gases toeither one or all of the other furnace chambers for the treatment of themetal or metal alloy at relatively lower temperatures. In general it isour aim and purpose to provide a multiple furnace structure of the abovecharacter which? may be advantageously employed for first pre-heatingthe metal object, then subjecting the same to a high temperature heattreatment, and sub 1921. Serial No. 66,780.

ment of our invention and in which similar reference charactersdesignate corresponding` parts throughout the several viewsigure 1 is alon 'tudinal sectional view throu h a .multiple c ambered furnacestructure isclosing a preferable embodiment of the invention.

Figure 2 is a topl plan view.

'Fi re 3 is a transverse section taken on the line 3 3 of Figure 2.

In the resent art of heat treating high speed stee s, it is the usualpractice to first heat the steel object in a pre-heatin oven type offurnace and then to trans er the object to a high temperature oven typefurnace where it is heated to a temperature of 2100 degrees F. to 2200degrees F., as may be required owing to the composition of theparticular metal alloy. The metal piece or object after being subjectedto the high temperature heat treatment is then suddenly quenched in analloy bath at ordinary room temperature, the piece is finally drawn in alead bath to about 1100 degrees F. This practice is sometimes modifiedby first preheating in an oven type furnace, then heating the piece tothe required hi h temperature in a bath of barium chlori e, and then'uenchin a ove re erred to.

A further development in' the present art is to pre-heat the metal piecein an oven type furnace and then subject the piece to the required hightemperature treatment in a high temperature oven type furnace, thenquench in a lead bath at about 1100 degrees F., and finally subquench inoil. This high temperature quench of the metal piece renders unnecessarythe drawing operation after the quench.

In the operation and use of our new furnace structure for the hightemperature heat treatment of metals, it is our practice to employeither one hi h temperature bath con- '-CHUSLTTS, .AND CHARLIE S.COLLINS, .OF BRONX, NEW YORK, ASSIG-NOBS A and drawing in an oil bath asI sisting of fused sa ts, preferably of eutectic v lication of Arthur E.Bellis filed, Septemlier 24, 1920, Serial No. 412,588, and one quenchbath also consisting of an eutectic mixture of fused salts likewisereferred to in said pending a plication, or on the other hand to use apreeating bath likewise consisting of an eutectic mixture of fusedsalts, a high temperature bath of fused salts and a quench bath of fusedsalts, each of the said salt baths having the characteristics of aneutectic as described in the said Bellis application.

In order to obviate distress or physical deteriorationv of the metalpots or containers for the salt baths, and more particularly those usedin' the high temperature chamber of .the furnace, We employ the specialCrucible construction of Patent No. 1,358,816 granted to Arthur E.Bellis, November 16th, 1920, and the protecting or sealing rings asshown and described in the pending application of Charles S. Collins,.Serial No. 406,870, filed August 30th, 1920.

Referring now in detail to the accompanying drawings 5 designates thebody of the furnace structure which may be of fire brick, masonry orother more or less refractory material, said body structure beingreinforced and supported by the metallic frame Work 6 and mounted upon aplurality of-pedestals or supports 7. In the present illustratedembodiment of our invention We have shown this furnace structure asprovided with 3 chambers, namely, a pre-heating chamber 8, a hightemperature chamber 9 and the quench chamber 10.

These chambers may be of any desired size and shape. Each, chamber opensthrough the vtop of the furnace and through such opening the bathcontaining pot or crucible generally indicated at 11 may be inserted.Preferably the pot which is arranged in the high temperature chamber 9is provided with an exterior wall 12 whichis more or less resistant tooxidizing atmospheres and serves as a protection for the inner liner ormetal pot proper, in accordance with the patented Bellis crucibleconstruction previously referred to.

A 'suitably proportioned mixture of air and gas is supplied to the hightemperature chamber 9 through the medium of the burners 13. .In thepresent disclosure we have shown three of these burners arranged in oposite sides of the furnace structure and de ivering the 4mixture of airand gas into the chamber atopposite sides of the crucible arrangedtherein. An opening indicated at 14 is formed through one side of thefurnacethrough' which a lighted taper may be inserted for the purpose ofigniting the gaseous mixture issuing from the burners.

Auxiliary burners 15 and 16 respectively areJ provided for thepreheating and quench- 'ing chambers of the furnace'structure, and

Laender the lighting openings 17 and 18respectively communicate withthese chambers through which the taper may be inserted for igniting thegas. However, as will be hereinafter explained these auxiliary burnersare not used except upon the start of operations or when it is desiredto increase the temperatures in these chambers.

The furnace structure 5 is provided with the lpassages 19 and 20respectively which connect the central high temperature chamber 9 withthe chambers 8 and 10, said passages being located at the lower ends ofthe furnace chambers. The outlet iues or passages 21 and 22 respectivelyextends upwardly through the furnace structure from the passages 19 and20 and open through the top of the furnace. The up er ends of theseoutlet flues may be closed y means of suitable plates or closures.Additional outlet passages 23 and 24 respectively connect with the upperends of the preheating and quench chambers 8 and 10 and open through thetop of the furnace structure. Suitable dampers indicated at 25 areprovided for the purpose of controllingl the passage of the products ofcombustion from the central preheating chamber 9 into the passages 19and 20, thus enabling all of these 'products to be passed into eitherone of the chambers 8 or 10 or to be equally distributed to saidchambers.

The furnace structure is4 further provided With drainage openings 26communicating with the lower end of each of the chambers through whichany overflow from the crucibles may be drained 0H'.

In the operation of our improved multiple type furnace as abovedescribed, the salt bath solution contained in the crucible in thecentral chamber 9 of the furnace is .maintained at a temperature offrom'2000 to 2300 degrees F., as may be required by lthe particular workin hand. This temperature of thel bath solution necessitates acombustion chamber temperature of about 2500 to 2700 degrees F., and theroducts of combustion leaving this cham er are usually above 2200degrees F. If these gases were allowed to escape to the atmospherewithout utilizing the heat energy contained therein, a great waste offuel would result.

'Howeveig by means of our improved furnace structure, We conduct thesehigh temperature waste gases from the central chamber 9 to thepreheating chamber 8 vand the quench chamber 10. We have found inpractice that there is suiiicient heat contained in these waste gases tomaintain the required temperature of the preheating bath solution.namely, approximately 1600 degrees F.. and likewise the requiredtemperature of the quench bath solution, namely, approximately 1300degrees F. These temperatures in the preheating and quenching baths maybe of air.

attained at thel start of operations by using the auxiliary burners 15and 16 respectively or if at any time it is desired to increase thesetelnperatures then the auxiliary burn-l ers are employed. Thetemperatures in the pre-heating and quench chambers can' also be variedand controlled by the proper manipulation of the dampers 25.

the metal ofthe pot and cause scaling.

Furnaces as now used in the'high temperature treatment of metals areprovided with vents at the top of the furnace chamber so that free aircan pass through the furnace, such air entering at the'burner openingsat the bottom of the furnace chaniber. This free atmospheric air in itspassage through the chamber causes rapid oxidi'zation and scaling ofthe' pot wall after the fuel h as been turned off and while the pot andits contents are cooling.

In the operation of our new furnace construction we firethe central hightemperaf turechamber in the upper area and the waste gases are passed tothe end chambers and' then out to the atmosphere at the top of these-end chambers] It will therefore be manifest that there is no draft-effect through this central chamber to cause atmospheric air to enterthe furnace when the fuel supply is cut o ff. In order to control andmaintain a reducing atmosphere in the furnace chamber, we employ asystem which produces a constant ratio of air to gas irrespective of therate of fiow, and adjust the system so as to provide a reducingatmosphere. Our preferred embodiment of such a system of firing is fullyshown and described in Letters Patent 1.290.513 granted January 17,1919, to Charles S. Collins and Louis Roessel.A The adaptation of thisproportional regulating system for the air and `gas flow to ourirnproved furnace structure will be readily perceived upon a perusal ofthe said patent.

From the foregoing". description con- K sidered in connection with theaccompanying drawings, the construction,.manner of operation and severaladvantages of our 1mproved multiple type furnace will be' clearlyunderstood 'IVe ,have successfully demonstrated in practice that such afurnace construction results in great. economv in the high temperatureheattreatment of It is therefore evident metals, first bythe appreciablereduction in fuel consumption due to the fact that -a great part of theheat lin thegases leavin the high temperature chamber is utilize forheating the llower temperature preheating and quench bath chambers, andsecondly, by prolonging the life of the pots or crucibles which arelused in connection with the furnace. The maintenance of proper'temperatures inA the three furnace chambers is always under the controlof the operator by the simple manipulation of the \fuel flow regulatingvalves and the adjusti ment of the waste gas control dampers.

In the foregoing description we have set forth in detail the severalstructural features of'a multiple typelfurnace which we have found togive highly satisfactory results. Nevertheless, it is to be understoodthat this invention might also be exemplified in numerous other furnacestructures. Thus for instance,'instcad of producing the furnace intheform of a single unitary structure with the. series of. chambers,We'might provide separate and distinct furnaces each having a singlechamber,v more or less widely separated from eachother and connected bysuitable pipes or conduits constituting the equivalent of the Waste heatconducting passages or ilues. Further, as will be readily apparent toone skilled in the art the several detail parts of 4the irn- -provedfurnace might be variously changed or modified, and we thereforelreserve the privilege of resorting to all such legitimate alterationsin the form, proportion and relative arrangement of the several elementsof the described construction as may be fairly embodied within thespirit and scope of the invention as claimed.l

IVe claim: l 1. A furnace. for heat treating metals g having a hightemperature chamber from which free air is excluded, and preheating and.quench chambers ,open to the atmosphere, means for supplying acombustible .fuel mixture to -the high temperature chamber, and meansfor transferring llU . the products of combustion from said high A 2. Inthe heat treatment of metals, a high y temperature furnace .chamber andpreheating and quenchA chambers, each of said chambers adapted toreceive a Crucible containing a fused salt treatment bath, means of.affording communication between the 'several chambers at their lowerends, and meansfor supplying a combustible fuel miX- ture 'tol thehightemperature chamber, the productsvf combustion being conveyed fromsaid chamber through the communicating means to thepreheating and quenchchambers.

3. In the heat treatment of metals, a furn sages connecting the severall'chambers to each' other at their lower ends, sald high temper-'a1 turechamber-being closedto the atmospherenace structure 'having -a hi h'temperature chamber and preheating an quench chambers,- each of saidchambersadaptedtc receive a crucible containinga heat treatment bath,said furnace structurehaving passages connecting the several chambers toeach other at their lower ends, said high temperatur-e chamber beingclosed to the atmosphere and the reheating chamber and quench chambersavingvent openings at their upper ends and a plurality, of fuelburnersfor the high4 temperature chamber, the products ofcombusti'onbeing 'conducted by said pasto the preheating and .quench chambers. f Y

A. In the heat treatmentof metals, a fun nace structure having a' hightemperature chamber and preheating and-quench chambers, each of said'chambers'adapted to lreceive a crucible containinga heat treatmentbath, said furnace 'structure having passages 'bath solution and apassage connecting said chambers to each other at their lower ends, oneof said chambers being closed to the exterior air and the other of saidchambers having a vent opening at its upper end, and a plurality of fuelburners 4for the first named chamber arranged above said connectingpassage to heat the contents of the crucible to a high temperature, theproducts of combustion being conducted by said passage' from said hightemperature chamber to the other of the chambers to heat the `con tentsof the crucible therein -to lower temperature.

6. In the-heat treatment of metals, a furnace structure having spaced'chambers each adapted to receive a crucible containing a bath solutionand a passage connecting said chambers below the crucibles to each otherat their lower ends, one of said chambers being closed to the exteriorair and the other of said chambers having a vent opening at its upperen'd, a plurality of fuel burnersfor the iirst named chamber to heat thecontents of the crucible to a high temperature`- the products ofcombustion being conducted by said passage from said high temperature arelatively chamber to the other of the chambers to heatl the contents ofthe crucible therein to a rel.

atively lower temperature, and means for said chambers' attheiilowerends, the fur# nace structure being Q urth'er prov1ded with an outletli'ue 'communicating with said pas sage, Aone of'saidA 'chambers beingclosed to the exterioiffair andthe other chamber hav'd chamber to heatthecontents of the crucible l.therein to al 'high temperature, theproducts of combustion being conducted from said high ,temperaturechamber to the other of.

said chambers toheat the contents of the crucibletherein to a relativelylower tempera-ture. l

8. ln the heat treatment of metals, .a furnace structure having a hi htemperature quench chamchamber and preheating an bers, each of saidchambers adapted to receive a crucible containing a treatment'bath,

sages connecting said chambers to each other at their lower ends, thehigh temperature chamber being closed' to the exterior air and thepreheating and lquench ,chambers having vent openings at their upperends, a plurality of primary burners for the high temperaturechamberauxiliar burners for the preheating and quench c ambers, theproducts of combustion being conducted by said passages from the hightemperature chamber to the preheating and quench chambers, and means forcontrolling the distribution of the products of combustion'to the latterchambers.

Y 9. In the hea-t treatment of metals, a furnace structure having a hightemperature chamber and preheating and quench chambers, each of saidchambers adapted to receive a crucible containing a treatment bath, saidfurnace structure 'provided with passages connecting said -chambers toeach other at their lower ends, the high temperature chamber beingclosed tothe exterior air and the preheating and quench chambers havingvent openings at their vupper ends, a"

plurality of primary burners for the high temperature chamber,auz'riliary burners for the preheating' and' quench chambers, theproducts of combustion being conducted by said passages fromthe hightemperature chamber to the preheating and quench cham-- bers, saidfurnace structure being further provided with outlet' fluescommunicating with'said connecting passages, and means for controllingthe distribution of the products of,combus`tion Vto the latter chambers.

10. In the art of heat treating metals by means yof a plurality of fusedsalt solutions maintained at relatively different tempera fing la ventopening atl its upper end, and a 'plurality of-fuel burners for thefirst named Isaid furnace. structure provided' with pastures; the methodwhich consists in heatn testimony that We claim the fore oing ing thehigh temperature bath solution conas oui` invention, and we have signeoul taining crucible in a reducing atmosphere names hereunder. to therequisite temperature and utilizing the 5 exhausted heating medium forheating the LOUIS ROESSEL.

crucibles containing the relatively low tem- ARTHUR E. BELLS. peraturebath solutions. CHARLES S. COLLINS.

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